System and method for displaying an alignment ct

ABSTRACT

A system for navigating to a catheter to a target is disclosed. The system includes a probe and a workstation. The probe is configured to be navigated through a patient’s airways and includes a location sensor. The workstation is in operative communication with the probe. The workstation includes a memory and at least one processor. The memory stores a navigation plan and a program that, when executed by the processor, is configured to generate a 3D rendering of the patient’s airways, generate a view using the 3D rendering, and display the view featuring at least a portion of the navigation plan. Generating the view includes executing a first transfer function for a first range from a distal tip of the location sensor and executing a second transfer function for a second range from the distal tip of the location sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application Serial No.16/264,817, filed on Feb. 1, 2019, now U.S. Pat. No. 11,464,576, whichclaims the benefit of the filing date of provisional U.S. Pat.Application No. 62/628,560, filed on Feb. 9, 2018, the entire contentsof each of which are incorporated herein by reference.

BACKGROUND

Visualization techniques related to visualizing a patient’s lungs havebeen developed so as to help clinicians perform diagnoses and/orsurgeries on the patient’s lungs. Visualization is especially importantfor identifying a location of a diseased region. Further, when treatingthe diseased region, additional emphasis is given to identification ofthe particular location of the diseased region so that a surgicaloperation is performed at the correct location.

SUMMARY

The disclosure is directed to a system for navigating a surgical deviceto a target. The system includes a probe, which includes a locationsensor, configured to be navigated through a patient’s airways. Thesystem further includes a workstation in operative communication withthe probe. The workstation includes a memory and at least one processor.The memory stores a navigation plan and a program that, when executed bythe processor, is configured to generate a three-dimensional (3D)rendering of the patient’s airways, generate a view using the 3Drendering, and present a user interface that guides a user through thenavigation plan, the user interface configured to display the 3D view.To generate the view, the processor executes a first transfer functionfor a first range from the location sensor to generate one or moreairways within the 3D rendering and executes a second transfer functionfor a second range from the location sensor to generate the one or moretargets within the 3D rendering. One or more targets include one or morelesions.

In an aspect, the first transfer function is executed using a firstvoxel density, and the second transfer function is executed using asecond voxel density. The first and second ranges may include variousdistances and relationships between the ranges and may be determined atvarious times and in varying manners. For example, the first range maybe less than the second range. As an additional example, at least one ofthe first range and the second range may be predetermined or dynamicallycalculated based on a location of the one or more targets.

In further aspects of the disclosure, the processor is configured tocause further aspects and features to be displayed in the view. In anaspect, the processor is configured to determine intensity associatedwith the one or more targets and cause the intensity associated with thetarget to be displayed. Additionally, the one or more targets may bedisplayed in a maximal surface size in the view.

In an aspect, the processor is further configured to cause one or moremarkings to be displayed, for example overlaid, on the one or moretargets and to cause a crosshair to be displayed in the view to assistalignment to a center of the one or more targets.

In yet another aspect of the disclosure a system for navigating to atarget is provided. The system includes an electromagnetic trackingsystem having electromagnetic tracking coordinates, a catheterconfigured to couple to the electromagnetic tracking system, and acomputing device configured to operably coupled to the electromagnetictracking system and the catheter. The catheter includes a locationsensor for detecting a location of the catheter in the electromagnetictracking coordinates. The computing device is configured to generate athree-dimensional (3D) rendering of a patient’s airways, and generate a3D view by executing a first transfer function for a first range fromthe location of the catheter to identify one or more airways within the3D rendering and executing a second transfer function for a second rangefrom the location of the catheter to identify one or more targets withinthe 3D rendering. In an aspect, the computing device is configured todisplay the generated 3D view.

In an aspect, the catheter further includes and a pose sensor fordetecting a pose of the catheter in the electromagnetic trackingcoordinates.

In an aspect, at least one of the first range or the second range isdynamically calculated based on the location of the catheter relative tothe target.

In an aspect, the first range is less than the second range.

In an aspect, the computing device is configured to determine whether anumber of the one or more airways within the 3D rendering exceeds athreshold, and execute a modified transfer function to identify one ormore airways within the 3D rendering when it is determined that thenumber of the one or more airways within the 3D rendering does notexceed the threshold. The modified transfer function may include atleast one of a modified filtering threshold, a modified accumulation ofvoxels, or a modified projection range.

In yet another aspect of the disclosure, a method for navigating to atarget is provided. The method includes generating a three-dimensional(3D) rendering of a patient’s lungs, executing a first transfer functionfor a first range from a location of a probe within the patient’s lungsto identify one or more airways within the 3D rendering, executing asecond transfer function for a second range from the location of theprobe to identify one or more targets within the 3D rendering, andgenerating a 3D view based on the first transfer function and the secondtransfer function.

In an aspect, the method further includes displaying the 3D view.

In an aspect, the first range is less than the second range.

In an aspect, the method further includes determining whether a numberof the one or more airways within the 3D rendering exceeds a thresholdand executing a modified transfer function to identify one or moreairways within the 3D rendering when it is determined that the number ofthe one or more airways within the 3D rendering does not exceed thethreshold. In an aspect, executing the modified transfer functionincludes at least one of modifying a filtering threshold, modifying anaccumulation of voxels, or modifying a projection range.

Any of the above aspects and embodiments of the disclosure may becombined without departing from the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the disclosure are described hereinbelowwith references to the drawings, wherein:

FIG. 1 is a perspective view of an electromagnetic navigation system inaccordance with the disclosure;

FIG. 2 is a schematic diagram of a workstation configured for use withthe system of FIG. 1 ;

FIG. 3 is a flow chart illustrating a method of navigation in accordancewith an embodiment of the disclosure; and

FIG. 4 is an illustration of a user interface of the workstation of FIG.2 presenting a view for performing registration in accordance with thedisclosure.

DETAILED DESCRIPTION

The disclosure relates to systems and methods for internally guidednavigation of catheters based on a model generated from CT image data.

In the past, scanned two-dimensional (2D) images of the lungs have beenused to aid in visualization. In order to obtain the 2D images, apatient undergoes a CT scans. In addition to using scanned 2D images,three-dimensional (3D) models may also be used to virtually navigatethrough the body. The use of 3D models for navigation is more complexthan using 2D images and includes several challenges. One challengeinvolves guiding a catheter to the target in 3D. Many views have beendeveloped, some of them using cross-sections, and a proposed view isdesigned to assist with guidance. However, when one tries to lookthrough the whole volume from a point of view instead of looking at across-section, the view may be obstructed and objects, which are behindother objects, might not be seen. Methods have been developed toalleviate the obstructed view problem, such as adding transparency tosome of the volume or highlighting farther objects. One of the knownmethods involves Maximum Intensity Projection (MIP) which is a volumerendering method for 3D data that projects in the visualization planethe voxels with maximum intensity that fall in the way of parallel raystraced from the viewpoint to the plane of projection.

However, when using MIP to align an electromagnetic navigation cathetertowards a lesion, traditional methods may result in lesions locatedbeyond objects, such as bones or other non-soft tissue, not beingvisible. Therefore, there is a need to develop new view developmenttechniques that improve upon MIP.

The disclosure is related to devices, systems, and methods forinternally guided navigation of catheters based on a model generatedfrom CT image data to guide a catheter to a target. In the disclosure,the system provides a view of a defined section of a volume from theperspective of the catheter. To achieve the view disclosed in thecurrent application, two filters are separately applied to a rendered 3Dvolume. The filters isolate airway tissue and lesion tissue from the 3Drendering so that it can be combined in order to generate a view whichpresents only airways and lesions and eliminates obstacles such as boneswhich would ordinarily obscure a view from the catheter.

Alignment of catheter 102 may be a necessary component of pathwayplanning for performing an ELECTROMAGNETIC NAVIGATION BRONCHOSCOPY®(ENB) procedure using an electromagnetic navigation (EMN) system. An ENBprocedure generally involves at least two phases: (1) planning a pathwayto a target located within, or adjacent to, the patient’s lungs; and (2)navigating a probe to the target along the planned pathway. These phasesare generally referred to as (1) “planning” and (2) “navigation.” Theplanning phase of an ENB procedure is more fully described incommonly-owned U.S. Pat. Nos. 9,459,770; and 9,639,666 and U.S. Pat.Publication No. 2014/0270441, all entitled “Pathway Planning System andMethod,” filed on Mar. 15, 2013, by Baker, the entire contents of whichare hereby incorporated by reference. An example of the navigationsoftware can be found in commonly assigned U.S. Pat. Publication No.2016/0000302 entitled “SYSTEM AND METHOD FOR NAVIGATING WITHIN THE LUNG”the entire contents of which are incorporated herein by reference.

Prior to the planning phase, the patient’s lungs are imaged by, forexample, a computed tomography (CT) scan, although additional applicablemethods of imaging will be known to those skilled in the art. The imagedata assembled during the CT scan may then be stored in, for example,the Digital Imaging and Communications in Medicine (DICOM) format,although additional applicable formats will be known to those skilled inthe art. The CT scan image data may then be loaded into a planningsoftware application (“application”) to be used during the planningphase of the ENB procedure.

Embodiments of the systems and methods are described with reference tothe accompanying drawings. Like reference numerals may refer to similaror identical elements throughout the description of the figures. Thisdescription may use the phrases “in an embodiment,” “in embodiments,”“in some embodiments,” or “in other embodiments,” which may each referto one or more of the same or different embodiments in accordance withthe disclosure.

FIG. 1 illustrates an electromagnetic navigation (EMN) system 10 inaccordance with the disclosure. Among other tasks that may be performedusing the EMN system 10 are planning a pathway to target tissue,navigating a positioning assembly to the target tissue, navigating acatheter 102 to the target tissue to obtain a tissue sample from thetarget tissue using catheter 102, and digitally marking the locationwhere the tissue sample was obtained, and placing one or more echogenicmarkers at or around the target.

EMN system 10 generally includes an operating table 40 configured tosupport a patient; a bronchoscope 50 configured for insertion throughthe patient’s mouth and/or nose into the patient’s airways; monitoringequipment 60 coupled to bronchoscope 50 for displaying video imagesreceived from bronchoscope 50; a tracking system 70 including a trackingmodule 72, a plurality of reference sensors 74, and an electromagneticfield generator 76; a workstation 80 including software and/or hardwareused to facilitate pathway planning, identification of target tissue,navigation to target tissue, and digitally marking the biopsy location

FIG. 1 also depicts two types of catheter guide assemblies 90, 100. Bothcatheter guide assemblies 90, 100 are usable with the EMN system 10 andshare a number of common components. Each catheter guide assembly 90,100 includes a handle 91, which is connected to an extended workingchannel (EWC) 96. The EWC 96 is sized for placement into the workingchannel of a bronchoscope 50. In operation, a locatable guide (LG) 92,including an electromagnetic (EM) sensor 94, is inserted into the EWC 96and locked into position such that the sensor 94 extends a desireddistance beyond the distal tip 93 of the EWC 96. The location of the EMsensor 94, and thus the distal end of the EWC 96, within anelectromagnetic field generated by the electromagnetic field generator76 can be derived by the tracking module 72, and workstation 80.

FIG. 2 illustrates a system diagram of workstation 80. Workstation 80may include memory 202, processor 204, display 206, network interface208, input device 210, and/or output module 212. Workstation 80implements the methods that will be described herein.

FIG. 3 depicts a method of navigation using the navigation workstation80 and the user interface 216. At step S300 user interface 216 presentsthe clinician with a view (not shown) for the selection of a patient.The clinician may enter patient information such as, for example, thepatient name or patient ID number, into a text box to select a patienton which to perform a navigation procedure. Alternatively, the patientmay be selected from a drop down menu or other similar methods ofpatient selection. Once the patient has been selected, the userinterface 216 presents the clinician with a view (not shown) including alist of available navigation plans for the selected patient. At stepS302, the clinician may load one of the navigation plans by activatingthe navigation plan. The navigation plans may be imported from aprocedure planning software and include CT images of the selectedpatient.

Once the patient has been selected and a corresponding navigation planhas been loaded, the user interface 216 presents the clinician with apatient details view (not shown) At step S304 which allows the clinicianto review the selected patient and plan details. Examples of patientdetails presented to the clinician in the timeout view may include thepatient’s name, patient ID number, and birth date. Examples of plandetails include navigation plan details, automatic registration status,and/or manual registration status. For example, the clinician mayactivate the navigation plan details to review the navigation plan, andmay verify the availability of automatic registration and/or manualregistration. The clinician may also activate an edit button edit theloaded navigation plan from the patient details view. Activating theedit button of the loaded navigation plan may also activate the planningsoftware described above. Once the clinician is satisfied that thepatient and plan details are correct, the clinician proceeds tonavigation setup at step S306. Alternatively, medical staff may performthe navigation setup prior to or concurrently with the clinicianselecting the patient and navigation plan.

During navigation setup at step S306, the clinician or other medicalstaff prepares the patient and operating table by positioning thepatient on the operating table over the electromagnetic field generator76. The clinician or other medical staff position reference sensors 74on the patient’s chest and verify that the sensors are properlypositioned, for example, through the use of a setup view presented tothe clinician or other medical staff by user interface 216. Setup viewmay, for example, provide the clinician or other medical staff with anindication of where the reference sensors 74 are located relative to themagnetic field generated by the electromagnetic field generator 76.Patient sensors allow the navigation system to compensate for patientbreathing cycles during navigation. The clinician also prepares LG 92,EWC 96, and bronchoscope 50 for the procedure by inserting LG 92 intoEWC 96 and inserting both LG 92 and EWC 96 into the working channel ofbronchoscope 50 such that distal tip 93 of LG 92 extends from the distalend of the working channel of bronchoscope 50. For example, theclinician may extend the distal tip 93 of LG 92 10 mm beyond the distalend of the working channel of bronchoscope 50.

Once setup is complete, workstation 80 presents a view 400, as shown inFIG. 4 , via the user interface 216. CT image data is acquired anddisplayed at step 308. At step 310, the CT image data is registered withthe selected navigation plan. An example method for registering imageswith a navigation plan is described in the aforementioned U.S. Pat.Publication No. 2016/0000302.

At step S312, workstation 80 performs a volume rendering algorithm basedon the CT image data included in the navigation plan and positionsignals from sensor 94 to generate a 3D view 404 of the walls of thepatient’s airways as shown in FIG. 4 . The 3D view 404 uses aperspective rendering that supports perception of advancement whenmoving closer to objects in the volume. The 3D view 404 also presentsthe user with a navigation pathway providing an indication of thedirection along which the user will need to travel to reach the lesion410. The navigation pathway may be presented in a color or shape thatcontrasts with the 3D rendering so that the user may easily determinethe desired path to travel. Workstation 80 also presents a local view406 as shown in FIG. 4 that includes a slice of the 3D volume located atand aligned with the distal tip 93 of LG 92. Local view 406 shows thelesion 410 and the navigation pathway 414 overlaid on slice 416 from anelevated perspective. The slice 416 that is presented by local view 406changes based on the location of EM sensor 94 relative to the 3D volumeof the loaded navigation plan. Local view 406 also presents the userwith a virtual representation of the distal tip 93 of LG 92 in the formof a virtual probe 418. The virtual probe 418 provides the user with anindication of the direction that distal tip 93 of LG 92 is facing sothat the user can control the advancement of the LG 92 in the patient’sairways.

At step S314, catheter 102 is navigated through the airways. Catheter102 may be navigated through catheter guide assemblies 90, 100 untilcatheter 102 approaches the target. Alternatively, catheter 102 may benavigated independently of catheter guide assemblies 90, 100. Catheter102 is navigated via manipulation of handle 91 which can be manipulatedby rotation and compression. Once catheter 102 is located approximatethe target, steps S314-S316 begin in order to render a 3D volumeincluding locations of one or more airways and one or more targets.Until catheter 102 is located at the target, catheter 102 is furthernavigated, at step S314, using the 3D volume and locations of one ormore airways and one or more targets continually generated in stepsS314-S316.

At steps S316 and S320, a view including lungs and lesions is renderedby projecting, from the location and orientation (i.e., the perspective)of catheter 102, parallel beams which accumulate densities until theyencounter an opaque object (e.g., bone). The volume rendering isperformed in two steps: 1) collecting voxel data and 2) accumulating thevoxel data in the direction of the beams, which is projected from thelocation and orientation of catheter 102, until the beam is stopped, atwhich point the voxel data is added together.

Further at step S316, workstation 80 applies a first transfer functionto the volume rendered at step S314. The first transfer function isapplied to a limited range projected from the position of catheter 102.The limited range may be predefined or be dynamically calculated basedon a location of and/or distance to the target. Along the limited rangeprojected from the position of catheter 102, the first transfer functionaccumulates voxels which have a density and/or a color within a certainrange indicating that the pixel represents a wall of a patient’sairways. As a result of applying the first transfer function,workstation 80 generates a filtered volume rendering preferably showingthe patient’s airways.

Further at step S318, workstation 80 assesses the result of applying thefirst transfer function to the rendered volume. Workstation 80 may use,for example, image recognition software to determine whetherrecognizable, airway-shaped elements are visible in the filtered volumerendering. Alternatively, the filtered volume rendering may be presentedto the clinician such that the clinician may inspect the filtered volumerendering and determine whether airways are visible. The clinician maythen indicate on the user interface whether airways are visible. Ifeither workstation 80 or the clinician determines that airways are notvisible, the process returns to step S316 wherein the first transferfunction is re-applied to the volume rendering with a modified filteringthreshold, a modified accumulation of voxels, or a modified projectionrange. If, at step S316, either workstation 80 or the cliniciandetermines that a requisite number of airways are visible, the processproceeds to step S320.

At step S320, workstation 80 applies a second transfer function to thevolume rendered at step S314. The second transfer function is applied toan unlimited range projected from the position of catheter 102. Though,as a practical matter, it is likely that the projected range will belimited by the size of the rendered volume. The second transfer functionmay also be applied to a limited range projected from the position ofcatheter 102. Along the range projected from the position of catheter102, the second transfer function accumulates voxels which have adensity and/or a color within a certain range indicating that the pixelrepresents a target tissue such as a lesion. Applying the secondtransfer function to an unlimited range from the position of catheter102 allows voxels representing target tissue such as a lesion to bedetected and shown beyond opaque objects (e.g., bones). As a result ofapplying the second transfer function to the rendered volume,workstation 80 generates a filtered volume rendering preferably showingtarget tissues, including those located beyond bones and other opaqueobjects.

At steps S322, workstation 80 assesses the result of applying the secondtransfer function to the rendered volume. Workstation 80 may use, forexample, image recognition software to determine whether recognizable,airway-shaped elements are visible in the filtered volume rendering.Alternatively, the filtered volume rendering may be presented to theclinician such that the clinician may inspect the filtered volumerendering and determine whether airways are visible. The clinician maythen indicate on the user interface whether target tissue is visible. Ifeither workstation 80 or the clinician determines that target tissue isnot visible, the process returns to step S320 wherein the secondtransfer function is re-applied to the volume rendering with a modifiedfiltering threshold, a modified accumulation of voxels, or a modifiedprojection range. If, at step S322, either workstation 80 or theclinician determines that a target tissue is visible, the processproceeds to step S324.

Limiting the transfer functions to highlighted structures within thelimited range of the distal tip 93 may reduce the load on processor 204.By using a limited range, denser structures that may obscure the lesionmay be omitted permitting the lesion to be displayed. The secondtransfer function may be configured to cause lesions within the range tobe displayed in their maximal surface size permitting the user to aimfor the center of the target. As shown in alignment view 402, the secondtransfer functions may be tuned to highlight lesion-density tissue andfilter out most other densities in the CT volume, creating a clearerpicture in which lung lesions stand out over dark background. A marking408, e.g., a sphere or ellipsoid, may be used to represent the plannedtarget and is overlaid on the rendered volume to reduce risk of aligningto the wrong object. A crosshair 415 in the center of the view assiststhe user in aligning distal tip 93 with the center of the target. Thedistance 412 from the distal tip 93 to the center of the marked targetis displayed next to the crosshair 415, permitting the user to find thebest balance between alignment and proximity

At step S324, the filtered volume rendering generated by applying thefirst transfer function and the filtered volume rendering generated byapplying the second transfer function are combined in order to generatea display showing the patient’s airways and target tissue. An exampledisplays resulting from the combination are shown at FIG. 4 .

At step S326, the clinician or workstation 80 determines whether thecatheter is a located at the target. If the catheter is not located atthe target, the process returns to step S314wherein the cliniciancontinues to navigate the catheter toward the target. As the catheter isnavigated toward the target, the display volume is continually renderingand the first and the second transfer functions are applied to generatea view showing airways and the target.

In the embodiments, the alignment of catheter 102 using CT image dataand 3D models permits a better aiming experience over other CT volumerepresentations. Target areas of lesions may be shown from a distance,where a normal CT slice would not be useful. The embodiments permit auser to assess optimal balance between alignment/proximity, whichdefines the best location for catheter introduction. The view lookssimilar to CT images thereby assuring clinicians that the informationthey are looking at is real, permits aiming to various parts of thelesion structure, and assures users that they are at the planned target.In the 3D models, irrelevant structures in the range are reduced oreliminated, permitting the user to clearly identify the target.

FIG. 4 shows 3D view 404 which show walls of the patient’s airways. The3D view 404 uses a perspective rendering that supports perception ofadvancement when moving closer to objects in the volume. The 3D view 404also presents the user with a navigation pathway providing an indicationof the direction along which the user will need to travel to reach thelesion 410. The navigation pathway may be presented in a color or shapethat contrasts with the 3D rendering so that the user may easilydetermine the desired path to travel. Workstation 80 also presents alocal view 406 as shown in FIG. 4 that includes a slice of the 3D volumelocated at and aligned with the distal tip 93 of LG 92. Local view 406shows the lesion 410 and the navigation pathway 414 overlaid on slice416 from an elevated perspective. The slice 416 that is presented bylocal view 406 changes based on the location of EM sensor 94 relative tothe 3D volume of the loaded navigation plan. Local view 406 alsopresents the user with a virtual representation of the distal tip 93 ofLG 92 in the form of a virtual probe 418. The virtual probe 418 providesthe user with an indication of the direction that distal tip 93 of LG 92is facing so that the user can control the advancement of the LG 92 inthe patient’s airways.

Referring back to FIG. 1 , catheter guide assemblies 90, 100 havedifferent operating mechanisms, but each contain a handle 91 that can bemanipulated by rotation and compression to steer the distal tip 93 ofthe LG 92, extended working channel 96. Catheter guide assemblies 90 arecurrently marketed and sold by Covidien LP under the nameSUPERDIMENSION® Procedure Kits, similarly catheter guide assemblies 100are currently sold by Covidien LP under the name EDGE® Procedure Kits,both kits include a handle 91, extended working channel 96, andlocatable guide 92. For a more detailed description of the catheterguide assemblies 90, 100 reference is made to commonly-owned U.S. Pat.Application Serial No. 13/836,203 filed on Mar. 15, 2013 by Ladtkow etal., the entire contents of which are hereby incorporated by reference.

In FIG. 1 , the patient is shown lying on operating table 40 withbronchoscope 50 inserted through the patient’s mouth and into thepatient’s airways. Bronchoscope 50 includes a source of illumination anda video imaging system (not explicitly shown) and is coupled tomonitoring equipment 60, e.g., a video display, for displaying the videoimages received from the video imaging system of bronchoscope 50.

Catheter guide assemblies 90, 100 including LG 92 and EWC 96 areconfigured for insertion through a working channel of bronchoscope 50into the patient’s airways (although the catheter guide assemblies 90,100 may alternatively be used without bronchoscope 50). The LG 92 andEWC 96 are selectively lockable relative to one another via a lockingmechanism 99. A six degrees-of-freedom electromagnetic tracking system70, e.g., similar to those disclosed in U.S. Pat. No. 6,188,355 andpublished PCT Application Nos. WO 00/10456 and WO 01/67035, the entirecontents of each of which is incorporated herein by reference, or anyother suitable positioning measuring system, is utilized for performingnavigation, although other configurations are also contemplated.Tracking system 70 is configured for use with catheter guide assemblies90, 100 to track the position of the EM sensor 94 as it moves inconjunction with the EWC 96 through the airways of the patient, asdetailed below.

As shown in FIG. 1 , electromagnetic field generator 76 is positionedbeneath the patient. Electromagnetic field generator 76 and theplurality of reference sensors 74 are interconnected with trackingmodule 72, which derives the location of each reference sensor 74 in sixdegrees of freedom. One or more of reference sensors 74 are attached tothe chest of the patient. The six degrees of freedom coordinates ofreference sensors 74 are sent to workstation 80, which includesapplication 81 where sensors 74 are used to calculate a patientcoordinate frame of reference.

Also shown in FIG. 1 is catheter 102 which is insertable into thecatheter guide assemblies 90,100 following navigation to a target andremoval of the LG 92. The catheter 102 is used to collect one or moretissue samples from the target tissue. As detailed below, catheter 102is further configured for use in conjunction with tracking system 70 tofacilitate navigation of catheter 102 to the target tissue, tracking ofa location of catheter 102 as it is manipulated relative to the targettissue to obtain the tissue sample, and/or marking the location wherethe tissue sample was obtained.

Although navigation is detailed above with respect to EM sensor 94 beingincluded in the LG 92 it is also envisioned that EM sensor 94 may beembedded or incorporated within catheter 102 where catheter 102 mayalternatively be utilized for navigation without need of the LG or thenecessary tool exchanges that use of the LG requires. A variety ofuseable catheters are described in U.S. Pat. Publication Nos.2015/0141869 and 2015/0141809 both entitled DEVICES, SYSTEMS, ANDMETHODS FOR NAVIGATING A CATHETER TO A TARGET LOCATION AND OBTAINING ATISSUE SAMPLE USING THE SAME, filed Nov. 20, 2013 and U.S. Pat.Publication No. 2015/0265257 having the same title and filed Mar. 14,2014, the entire contents of each of which are incorporated herein byreference and useable with the EMN system 10 as described herein.

During procedure planning, workstation 80 utilizes computed tomographic(CT) image data for generating and viewing a three-dimensional model(“3D model”) of the patient’s airways, enables the identification oftarget tissue on the 3D model (automatically, semiautomatically ormanually), and allows for the selection of a pathway through thepatient’s airways to the target tissue. More specifically, the CT scansare processed and assembled into a 3D volume, which is then utilized togenerate the 3D model of the patient’s airways. The 3D model may bepresented on a display monitor 81 associated with workstation 80, or inany other suitable fashion. Using workstation 80, various slices of the3D volume and views of the 3D model may be presented and/or may bemanipulated by a clinician to facilitate identification of a target andselection of a suitable pathway through the patient’s airways to accessthe target. The 3D model may also show marks of the locations whereprevious biopsies were performed, including the dates, times, and otheridentifying information regarding the tissue samples obtained. Thesemarks may also be selected as the target to which a pathway can beplanned. Once selected, the pathway is saved for use during thenavigation procedure. An example of a suitable pathway planning systemand method is described in the aforementioned U.S. Pat. Nos. 9,459,770;and 9,639,666 and U.S. Pat. Publication No. 2014/0270441.

During navigation, EM sensor 94, in conjunction with tracking system 70,enables tracking of EM sensor 94 and/or catheter 102 as EM sensor 94 orcatheter 102 is advanced through the patient’s airways.

Referring back to FIG. 2 , memory 202 includes any non-transitorycomputer-readable storage media for storing data and/or software that isexecutable by processor 204 and which controls the operation ofworkstation 80. In an embodiment, memory 202 may include one or moresolid-state storage devices such as flash memory chips. Alternatively orin addition to the one or more solid-state storage devices, memory 202may include one or more mass storage devices connected to the processor204 through a mass storage controller (not shown) and a communicationsbus (not shown). Although the description of computer-readable mediacontained herein refers to a solid-state storage, it should beappreciated by those skilled in the art that computer-readable storagemedia can be any available media that can be accessed by the processor204. That is, computer readable storage media includes non-transitory,volatile and non-volatile, removable and non-removable media implementedin any method or technology for storage of information such ascomputer-readable instructions, data structures, program modules orother data. For example, computer-readable storage media includes RAM,ROM, EPROM, EEPROM, flash memory or other solid state memory technology,CD-ROM, DVD, Blu-Ray or other optical storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can be accessed by workstation 80.

Memory 202 may store application 81 and/or CT data 214. Application 81may, when executed by processor 204, cause display 206 to present userinterface 216. Network interface 208 may be configured to connect to anetwork such as a local area network (LAN) consisting of a wired networkand/or a wireless network, a wide area network (WAN), a wireless mobilenetwork, a Bluetooth network, and/or the internet. Input device 210 maybe any device by means of which a user may interact with workstation 80,such as, for example, a mouse, keyboard, foot pedal, touch screen,and/or voice interface. Output module 212 may include any connectivityport or bus, such as, for example, parallel ports, serial ports,universal serial busses (USB), or any other similar connectivity portknown to those skilled in the art.

Any of the described methods, programs, algorithms or codes may beconverted to, or expressed in, a programming language or computerprogram. A “Programming Language” and “Computer Program” is any languageused to specify instructions to a computer, and includes (but is notlimited to) these languages and their derivatives: Assembler, Basic,Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript,Machine code, operating system command languages, Pascal, Perl, PL1,scripting languages, Visual Basic, metalanguages which themselvesspecify programs, and all first, second, third, fourth, and fifthgeneration computer languages. Also included are database and other dataschemas, and any other meta-languages. For the purposes of thisdefinition, no distinction is made between languages which areinterpreted, compiled, or use both compiled and interpreted approaches.For the purposes of this definition, no distinction is made betweencompiled and source versions of a program. Thus, reference to a program,where the programming language could exist in more than one state (suchas source, compiled, object, or linked) is a reference to any and allsuch states. The definition also encompasses the actual instructions andthe intent of those instructions.

Although embodiments have been described in detail with reference to theaccompanying drawings for the purpose of illustration and description,it is to be understood that the inventive processes and apparatus arenot to be construed as limited thereby. It will be apparent to those ofordinary skill in the art that various modifications to the foregoingembodiments may be made without departing from the scope of thedisclosure.

1-20. (canceled)
 21. A system for navigating to a target, the system comprising: a catheter navigable within a patient’s airways; and a computing device operably coupled to the catheter, the computing device configured to: generate a view using a three-dimensional (3D) rendering of the patient’s airways by executing a first transfer function for a first range from a location of the catheter to identify one or more airways within the 3D rendering and executing a second transfer function for a second range from the location of the catheter to identify one or more targets within the 3D rendering, the second transfer function configured to distinguish between a density of the one or more targets and a density of structures other than the one or more targets, wherein the second transfer function causes the generated view to omit structures other than the one or more targets located beyond the range of the first transfer function to avoid obscuring the view of the one or more targets within the 3D rendering based upon the differing densities between the one or more targets and the structures other than the one or more targets.
 22. The system according to claim 21, wherein the first transfer function is executed using a first voxel density, and the second transfer function is executed using a second voxel density.
 23. The system according to claim 21, wherein the first range is less than the second range.
 24. The system according to claim 21, wherein at least one of the first range and the second range is predetermined.
 25. The system according to claim 21, wherein at least one of the first range and the second range is dynamically calculated based on a location of the one or more targets.
 26. The system according to claim 21, wherein the one or more targets include one or more lesions.
 27. The system according to claim 21, wherein the view includes a mark overlaid on the one or more targets.
 28. The system according to claim 21, wherein the view includes a crosshair to assist alignment to a center of the one or more targets.
 29. A method for navigating to a target, the method comprising: executing a first transfer function for a first range from a location of a probe within the patient’s lungs to identify one or more airways within a three-dimensional (3D) rendering of the patient’s airways; executing a second transfer function for a second range from the location of the probe to identify one or more targets within the 3D rendering, the second transfer function configured to distinguish between a density of the one or more targets and a density of structures other than the one or more targets; and generating a 3D view based on the first transfer function and the second transfer function, wherein the second transfer function causes the generated 3D view to omit structures other than the one or more targets located beyond the range of the first transfer function to avoid obscuring the view of the one or more targets within the 3D rendering based upon the differing densities between the one or more targets and the structures other than the one or more targets.
 30. The method according to claim 29, further comprising displaying the 3D view featuring the identified one or more airways, the identified one or more targets, and at least a portion of a navigation plan.
 31. The method according to claim 29, wherein the first range is less than the second range.
 32. The method according to claim 29, further comprising: determining whether a number of the one or more airways within the 3D rendering exceeds a threshold; and executing a modified transfer function to identify one or more airways within the 3D rendering when it is determined that the number of the one or more airways within the 3D rendering does not exceed a threshold.
 33. The method according to claim 29, wherein executing the modified transfer function includes at least one of modifying a filtering threshold, modifying an accumulation of voxels, or modifying a projection range.
 34. The method according to claim 29, further comprising dynamically calculating at least one of the first range or the second range based on a location of the one or more targets.
 35. The method according to claim 29, further comprising displaying the 3D view featuring a mark overlaid on the identified one or more targets.
 36. A system for navigating to a target, the system comprising: a catheter navigable within a patient’s airways, the catheter including a location sensor for detecting a location of the catheter within the patient’s airways; and a computing device operably coupled to the catheter, the computing device configured to: generate a 3D view using image data of the patient’s airways by executing a first transfer function for a first range from the location sensor to identify one or more airways within the image data and executing a second transfer function for a second range from the location sensor to identify one or more targets within the image data, the second transfer function configured to distinguish between a density of the one or more targets and a density of structures other than the one or more targets, wherein the second transfer function causes the generated 3D view to omit structures other than the one or more targets located beyond the range of the first transfer function to avoid obscuring the view of the one or more targets within the image data based upon the differing densities between the one or more targets and the structures other than the one or more targets.
 37. The system according to claim 36, wherein the catheter includes a pose sensor for detecting a pose of the catheter within the patient’s airways.
 38. The system according to claim 36, wherein the computing device is configured to display the 3D view featuring the identified one or more airways, the identified one or more targets, and at least a portion of a navigation plan.
 39. The system according to claim 36, wherein at least one of the first range or the second range is dynamically calculated based on the location of the catheter relative to the target.
 40. The system according to claim 36, wherein the computing device is configured to: determine whether a number of the one or more airways within the image data exceeds a threshold; and execute a modified transfer function to identify one or more airways within the image data when it is determined that the number of the one or more airways within the image data does not exceed the threshold. 